A polyvinyl chloride resin, which is a homopolymer or a copolymer including 50% or more of polyvinyl chloride, is a commonly-used resin which can be formed into various products by extrusion molding, injection molding, calendering or the like. Such a polyvinyl chloride resin is widely used as a raw material for various products, such as pipes, electric wires, electric appliances, toys, films, sheets, synthetic leathers, tarpaulins, tape, packing materials for foods, medical supplies and the like. Various physical properties can be provided to such a polyvinyl chloride resin by suitably adding various additives such as a plasticizer, a stabilizer, filler, pigment and the like.
Among such additives, a plasticizer is an essential additive providing various physical properties and functions, such as workability, flexibility, electrical insulation, adhesivity and the like, to a polyvinyl chloride resin. Low volatility, as a very important factor of a plasticizer, is important both when a plasticizer is mixed in a plastic composition and when a shaped product containing a plasticizer is practically used. Further, plasticizers used in the field of foods, drinks, medical supplies and medicines must be harmless to the human body for health. A typical example of such harmless plasticizers is a phthalate plasticizer. However, it is predicted that the usage of a phthalate plasticizer will be remarkably reduced in the future because of the criticism regarding its toxicity attributable to its reactivation under the laws regulating toxic materials. Therefore, it is required to develop a plasticizer that includes an ester whose basic structure does not contain phthalate and which has a plasticizing efficiency equal to that of a phthalate plasticizer.